A cushion body is included in skin materials of passenger seats of automobiles or trains, various kinds of sofas, office chairs, and the like. As this cushion body, a molded body called rock wool, for example, which is obtained by entangling palm fibers and flax or stiff fibers such as thick synthetic fibers and hardening the same using rubber or the like, or a molded body (foam body) made from various kinds of expandable resin materials are used.
These cushion bodies have a curved face composed of convex and concave shapes satisfying ergonomic factors in order to maintain a seating posture which provides no fatigue despite long-hour seating. If it is intended to effectively manufacture the cushion bodies having such a complicated surface shape in large quantities considering its cushion performance, the aforementioned rock wool that requires a number of manufacturing processes cannot meet the demand.
In contrast, cushion bodies made from expandable resins have been used widely because it can be manufactured in a single process and various shapes can be obtained easily. That is, the cushion body made from expandable resins is molded into a desired shape at the same time as expansion molding when an expandable resin material such as expandable urethane resin is flown into a mold.
Further, the surface of the cushion body molded in this manner is generally deposited with a skin material such as various kinds of fiber cloth or natural or synthetic leather. In order to deposit the skin material on the surface of the cushion body, either a means for allowing a skin material to be adsorbed along a cavity surface of a mold and flowing an expandable resin material into the mold so that the cushion body is integrated with the rear surface of the skin material at the same time as molding of the cushion body or a means for molding a cushion body into a desired shape and covering and fixing a skin material to the surface of the cushion body has been employed.
In the case of using the means of integrating at the time of molding, as mentioned above, when a skin material is set along the inner surface of the mold, the skin material is adsorbed along the inner surface of the mold using an adsorption means. However, in order to deform the skin material so as to conform to the surface of the cushion body having a complex surface shape as described above, the skin material itself needs to be a material that has excellent elasticity. However, since there is a limit in the elasticity depending on a material, when the surface shape of the cushion body is complex, a number of wrinkles are likely to occur between the seating surface and the peripheral side surface in particular, and a lot of efforts have to be made to correct this.
According to this means, since the cushion body and the skin material are integrated on the entire surface, for example, when a strong force is applied in a direction where the skin material is shifted on the surface of the cushion body during use, a shearing force is applied between the skin material and the cushion body, a portion of the cushion body may be broken and the skin material may be separated. Further, a material that can be used as the skin material is naturally limited in order to eliminate the occurrence of wrinkles, and it is preferable to allow a slight movement between the skin material and the cushion body so that an excessive force is not applied between the skin material and the cushion body. Thus, instead of using the means for integrating the skin material at the same time as molding of the cushion body, a means of molding the cushion body in a desired shape and covering the obtained cushion body with the skin material has become popular.
In the case of covering the skin material on the cushion body made from an expandable resin material, a method of using a molding hook and loop fastener made from a thermoplastic resin is generally used. For example, first, a molding hook and loop fastener having a plurality of engaging elements (male engaging elements) is set on a cavity surface of a mold that performs molding of the cushion body. At this time, the molding hook and loop fastener is placed and fixed to a projecting surface portion on a bottom surface of the mold corresponding to a depressed surface of the cushion body so that an engaging element forming surface of the molding hook and loop fastener faces the projecting surface portion.
Subsequently, by expansion-molding the cushion body by an expandable resin material being flown into the mold in which the molding hook and loop fastener is set, at the same time as the molding of the cushion body, the molding hook and loop fastener is embedded in and integrated with the depressed surface of the cushion body in a state where the engaging elements are exposed to the outside. During this expansion molding, it is important to prevent the expandable resin material of the cushion body from flowing up to the engaging element forming region of the molding hook and loop fastener.
The skin material made from various kinds of materials such as pile woven/knit fabric, natural leather and synthetic leather which are previously formed in a bag shape corresponding to the outer shape of the cushion body is covered on the surface of the cushion body obtained by the expansion molding described above. In this case, the female engaging elements disposed on the rear surface of the skin material are pressed against the engaging element forming surface of the molding hook and loop fastener that is integrated with the cushion body so that the skin material is fastened along the depressed surface of the cushion body. In this way, the skin material is prevented from floating from the cushion body.
In expansion molding for integrating the molding hook and loop fastener into the cushion body, a technique of preventing the expandable resin material from entering into the engaging element forming region of the molding hook and loop fastener during molding of the cushion body is disclosed, for example, in JP 2005-211198 A (Patent Document 1), WO 2010/016122 A (Patent Document 2), and U.S. Pat. No. 6,720,059 (Patent Document 3), and the like.
A molding hook and loop fastener disclosed in Patent Document 1 includes a planar substrate, first resin-entrance preventing walls disposed on left and right side edges along the length direction of the substrate, a number of engaging elements disposed between the first left and right resin-entrance preventing walls, and a second resin-entrance preventing wall that is disposed in a width direction of the substrate so as to partition the engaging elements into necessary regions in the length direction of the substrate.
In the molding hook and loop fastener disclosed in Patent Document 1, three rows of vertical wall arrays are disposed alternately in the first resin-entrance preventing wall, and a divided vertical wall piece having a height dimension smaller than that of the vertical wall array is disposed between the three rows of vertical wall arrays. Further, the engaging element of which the engaging head extends back and front in the length direction is disposed to be integrated with the second resin-entrance preventing wall.
According to the molding hook and loop fastener disclosed in Patent Document 1, due to the first resin-entrance preventing wall disposed to extend in the length direction of the substrate and the second resin-entrance preventing wall disposed in the width direction of the substrate, it is possible to prevent a foaming resin material from entering into the engaging element forming region of the substrate when the cushion body is expansion-molded.
In particular, in Patent Document 1, the vertical wall arrays of each row that constitute the first resin-entrance preventing wall are disposed intermittently, and the vertical wall arrays of the adjacent rows are disposed in such a positional relation that the vertical wall arrays overlap in the width direction. Due to this, the gaps between the vertical wall arrays of the first resin-entrance preventing wall are formed in a zigzag form while appropriately maintaining the flexibility of the molding hook and loop fastener. Even if the foaming resin material tries to enter into the engaging element forming region of the substrate through the gaps of the first resin-entrance preventing wall when the cushion body is expansion-molded, it is possible to easily stop the entrance of the foaming resin material in the middle of the gaps formed in a zigzag form in the first resin-entrance preventing wall. Further, in Patent Document 1, since the second resin-entrance preventing wall itself includes the engaging elements, it is possible to prevent a decrease in the bonding strength between the molding hook and loop fastener and the skin material due to the presence of the second resin-entrance preventing wall.
On the other hand, a molding hook and loop fastener disclosed in Patent Document 2 includes a planar substrate, resin-entrance preventing walls disposed on left and right side edges along a length direction of the substrate, a number of engaging elements disposed between the left and right resin-entrance preventing walls, and a linear magnetic body disposed along the length direction of the substrate. Moreover, each of the left and right resin-entrance preventing walls includes a pair of first and second magnetic body clamping portions that is disposed at a predetermined interval along the length direction of the substrate so as to clamp the linear magnetic body, an outer wall portion disposed on an outer side of the first and second magnetic body clamping portions, and a supporting portion that supports, from below, the linear magnetic body protruding from the surface of the substrate and clamped by the first and second magnetic body clamping portions.
According to the molding hook and loop fastener of Patent Document 2, since the linear magnetic body is clamped by the first and second magnetic body clamping portions and is supported by the supporting portion from below, the linear magnetic body can be disposed near the distal ends of the first and second magnetic body clamping portions located distant from the substrate. Thus, when magnets are embedded at a fastener mounting position of a mold, for example, if the linear magnetic body of the molding hook and loop fastener is disposed near the distal ends of the first and second magnetic body clamping portions as described above, since the attracting force between the magnets of the mold and the linear magnetic body of the molding hook and loop fastener becomes strong, the molding hook and loop fastener can be properly adhered to and held by the mold. As a result, it is possible to prevent the occurrence of a gap between the molding hook and loop fastener and the cavity surface of the mold and to effectively suppress the foaming resin material from entering into the engaging element forming region of the substrate.
In Patent Document 3, preventing wall portions having various shapes for preventing a foaming resin material from entering into an engaging element forming region of a substrate are proposed as the resin-entrance preventing walls disposed on the left and right side edges of a planar substrate.